In a hybrid electric vehicle (HEV), either or both of an internal combustion engine and an electric motor are capable of supplying power to the wheels of the vehicle. Many HEV's also include planetary gear sets. For example, in a power-split hybrid vehicle, a planetary gear set is coupled to the engine and to a generator that generates power for an electric motor and battery. The planetary gear set may include a sun gear, a ring gear, and planet gears within a planetary carrier. Torque is delivered from the engine through the planetary gear set when any two of the three components lock together (“lockup”). Unintentional lockup may occur in which components of the planetary gear set lockup at undesired times. This may provide an unintentional boost in torque to the wheels from the engine. There is currently a need to effectively detect a lockup in the planetary gear set. There is also a need to mitigate the lockup condition and prevent over delivery of torque at the wheels of the vehicle.